The present invention relates to a piezoelectric weighing device and, more particularly, to a piezoelectric device that determines a ratio of weights during a manufacturing process without ever determining the actual weights. By operating on a leading edge of a resonant frequency for the piezoelectric device, a first electrical signal output representative of weight applied to the piezoelectric device can be easily measured. After removing part of the weight applied by a convenient means, such as evaporation by heat, the weight of the residue remaining represented by a second electric signal is determined. A ratio of the second electrical signal to the first electrical signal gives the percent of the residue remaining by weight.